Evidence for the Operation of the Hanle and Magneto-optical Effects in the Scattering Polarization Signals Observed by CLASP2 across the Mg II h and k Lines
Additional information
Authors
Ishikawa R.,
Trujillo Bueno J.,
Alsina Ballester E.,
Belluzzi L.,
del Pino Alemán T.,
McKenzie D. E. .,
Auchère F.,
Kobayashi K.,
Okamoto T. J. .,
Rachmeler L. A. .,
Song D.
Type
Journal Article
Year
2023
Language
English
Abstract
Radiative transfer investigations of the solar Mg II h and k resonancelines around 280 nm have shown that, while their circularpolarization (Stokes V) signals arise from the Zeeman effect,the linear polarization profiles (Stokes Q and U) are dominatedby the scattering of anisotropic radiation and the Hanle andmagneto-optical (MO) effects. Using the unprecedentedobservations of the Mg II and Mn I resonance lines obtained bythe Chromospheric LAyer Spectro-Polarimeter (CLASP2), here weinvestigate how the linear polarization signals at differentwavelengths (i.e., at the center, and at the near and far wingsof the k line) vary with the longitudinal component of themagnetic field (B $_ L $) at their approximate height offormation. The B $_ L $ is estimated from the V signals in theaforementioned spectral lines. Particular attention is given tothe following quantities that are expected to be influenced bythe presence of magnetic fields through the Hanle and MOeffects: the sign of the U signals, the total linearpolarization amplitude (LP) and its direction(ensuremathchi) with respect to a reference direction. Wefind that at the center and near wings of the k line, thebehavior of these quantities is significantly different in theobserved quiet and plage regions, and that both LP andensuremathchi seem to depend on B $_ L $. Theseobservational results are indicative of the operation of theHanle effect at the center of the k line and of the MO effectsat the near wings of the k line.
Journal
Astrophysical Journal
Volume
945
Number
2
Start page number
125
